1. Field of the Invention
The present invention relates to a contour filling apparatus and, more particularly, to an apparatus for filling the interior of shapes displayed on a display device.
2. Prior Art
FIG. 36 is a block diagram of a prior art contour filling apparatus illustratively disclosed in Japanese Patent Laid-open No. 56-142585. In FIG. 36, a display device 1 displays a target shape; a display frame memory 2 stores in bit-map format the shape to be displayed on the display device 1; and a display controller 3 controls the drawing in the display frame memory 2.
How the above prior art contour filling apparatus works will now be described. FIG. 37 is a view depicting how the interior of a shape is filled by the apparatus. In FIG. 37, reference numeral 4 is the contour of the shape to be displayed, and 5 is a scan starting point inside the contour 4.
The contour 4 of the shape to be displayed on the display device 1 is drawn in the display frame memory 2. The display device 1 displays the contour 4 based on the contents of the display frame memory 2. From the starting point 5 of a given line inside the contour 4, the display controller 3 starts scanning illustratively in the positive direction of the X axis. While performing the scan, the display controller 3 fills the applicable dots one by one in the display frame memory 2, until the contour 4 is reached. On detecting the contour 4, the display controller 3 returns to the starting point 5. From there, the display controller 3 similarly performs a scan in the negative direction of the X axis and fills the applicable points one by one. When the current line has been filled, the display controller 3 goes to another starting point 5 which is illustratively located one point away in the positive direction of the Y axis. Then the same process is repeated so as to fill the applicable dots of the line.
When the current starting point 5 has reached the contour 4, the display controller 3 returns to the initial starting point and performs the same process in the negative direction of the Y axis, shifting one point per scan. If there remains a portion yet to be filed after the lines in the negative direction of the Y axis have been filled, a scan starting point 5 is set anew in the interior of that portion, and the same process is again carried out. The interior of the contour 4 displayed on the display device 1 is filled consecutively in keeping with the filling in the display frame memory 2.
The prior art contour filling apparatus of the above-described construction emphasizes high-speed filling and draft memory reductions. One disadvantage of this apparatus is that because shapes are filled in a scan pattern (e.g., horizontal direction) specific to the apparatus, the filling process is executed only in a uniform manner.